There are many situations where there is a requirement to replace or repair pipelines in densely populated areas or inaccessible areas. The normal procedure for many years, which is particularly troublesome in congested cities, is to close off a street, dig up a buried damaged pipeline, install the new pipeline and repair the street. This is commonly done with city sewer and storm drain lines. However, there are many other areas where inaccessible faulty pipelines need to be relined.
To reduce the need to dig a trench along the entire length of the pipeline to be replaced, this has been overcome by a process of inserting within a pipeline requiring replacement a plastic pipe liner. Such a method of relining sewer pipe is disclosed in Bremner, U.S. Pat. No. 3,602,263. In his method as particularly directed to the relining of sewer mains, a reaming device is first passed through the old sewer line to remove tree roots, calcium deposit caked on the pipewalls and the like. A plastic pipe is passed through the reamed sewer line, the plastic pipe being of a lesser diameter than the reamed sewer line to form the new interior for the sewer line. The plastic piping, as fed into the sewer line, is commonly of polyethylene pipe where lengths of pipe are interconnected by the process of butt fusion welding, where the ends of pipe lengths to be joined are melted and in their softened state, connected to one another. Depending upon the length of the sewer line to be relined, this determines the number of pipe sections which are joined together. Commonly the pipe sections are of fifty foot lengths and are interconnected by using expensive, difficult to operate butt fusion welding equipment. Such equipment requires skilled personnel on the job site.
Another approach in relining sewer lines and other buried service pipelines is disclosed in Levens, U.S. Pat. No. 3,950,461 and St. Onge, Canadian patent No. 1,033,197. In these patents, improved techniques are disclosed for connecting lateral sewer lines to a relined main sewer line. Such interconnection is made from a remote location within the house or building via the lateral sewer line.
The drawback of the above processes for relining buried pipelines is that, aside from the requirement of butt fusion welding to interconnect lengths of pipe to be drawn into the pipeline to be relined, it still requires excavation and interruption to the flow of vehicle traffic.
As to the aspect of interconnecting pipe sections, mechanical interconnection of pipe sections have been used, such as in the oil drilling field. Drill strings are mechanically interconnected as shown in Knox et al, U.S. Pat. No. 3,359,013, Duret, U.S. Pat. No. 3,508,771 and Hokanson et al, U.S. Pat. No. 3,667,784. However, in these arrangements the drill strings or casing joints are formed of steel and would be totally unacceptable for use in relining buried pipeline, because of their rigidity. Insofar as mechanical interconnection of larger diameter plastic pipe is concerned, clamps have been used, for example, as supplied by DuPont Canada and sold under the trademark Sclairloc. Such couplings add large projections to pipe exterior making it unacceptable for relining pipelines by insertion renewal.
The method, according to this invention, provides for the relining of buried pipeline, where access thereto is difficult or impossible by excavation. The method provides for relining the pipeline without disturbing the surrounding street vehicle traffic by taking advantage of already provided accesses to the buried pipelines such as by manholes.